Such electric cells which are known, in particular through published French Pat. No. 2,166,015 (72 46158), have a very high energy density and their discharge voltage is about 3 volts. This makes it very desirable to use them. However, their disadvantage is that they reach their discharge voltage plateau only after a period of time due to the necessity of destroying the protective layer which passivates lithium in contact with thionyl chloride.
Efforts have been made to reduce this disadvantage. Thus published French Pat. No. 2,305,863 (76 08397) (U.S. Pat. No. 3,993,501) describes the lithium surface being covered with a layer of vinyl polymers which prevent passivating layers from forming. Also, in a paper read on the occasion of the 27th Power Sources symposium held in Atlantic City, it was recommended to add sulphur dioxide SO.sub.2 at a concentration of 5% to a solution of tetrachloroaluminate in thionyl chloride so as to reduce the delay effect in voltage rise of primary cells which use this solution as electrolyte solvent and positive active material.
However, none of these means has proved completely effective.
Preferred embodiments of the present invention improve the performance of lithium/thionyl chloride electric cells by reducing the time it takes for the voltage to rise, reducing said time until it becomes practically negligible.